Water infiltration into manholes has been a continuing problem with telephone companies, municipal public works departments and other public utility companies. For example, it is mandatory to segregate different types of municipal water systems. Statistics have shown that huge volumes of additional waste water must be treated because of water infiltrating into a sewer system via manholes. In the case of electric and gas utility underground systems, in many instances, almost continuous pumping of water is required before utility men can enter a manhole because of water infiltration through openings in the manhole cover or because the manhole cover forms an ineffective liquid seal.
Another, and equal problem, involves security of all underground systems using manhole frames and covers as entry stations. It has been a long-sought goal to provide strict locking security while also allowing easy authorized entry by respective personnel. Furthermore, locking the manhole cover into its respective frame has always been desirable because of high speed car, bus, and truck traffic on streets, arterials, and other expressway traffic.